Method and apparatus for detecting defective shells

ABSTRACT

A method and apparatus for detecting defective shells. A friction seal is placed in the open end of the shell and the shell is held on the seal while a limited quantity of gas is supplied to the inside of the shell at a pressure great enough to force the shell off the seal. The shell is then ceased to be held on the seal and will be forced off by the gas pressure if the gas has not escaped through a hole or the shell is not deformed. Many shells may be tested at the same time.

Elnited States Patent Spillane 1451 July 31, 1973 [54] METHOD ANDAPPARATUS FOR 527,989 4/l930 Germany 73/37 DETECTING DEFECTIVE SHELLSPrimary Examiner-Richard C. Queisser [75] Inventor. Matthew L. Spillane,Tamaqua, Pa. Assistant Examiner DeniS E. Co" [73] Assignee: AtlasChemical Industries, Iuc., Attorney-Kenneth E. Mulford and Roger R.Horton Wilmington, Del. 22 Filed: June 1, 1971 [57] ABSTRACT A methodand apparatus for detecting defective shells.

[2]] Appl' 148528 A friction sea] is placed in the open end of the shelland the shell is held on the seal while a limited quantity of [52] U.S.Cl. 73/49.2 gas is supplied to the inside of the shell at a pressure[51] Int. Cl. G0lm 3/02 great enough to force the shell off the seal.The shell is [58] Field of Search 73/9, 37, 49.2, 49.3 then ceased to beheld on the seal and will be forced off by the gas pressure if the gashas not escaped through [56] References Cited a hole or the shell is notdeformed. Many shells may be FOREIGN PATENTS OR APPLICATIONS 12/1915Germany 73/37 tested at the same time.

10 Claims, 4 Drawing Figures PATENIEDJULSI I975 SHEET 1 UP 4 INVENTORMatthew L. Spillane p- Bvrflw fi M ATTORNEY PATENIED JUL 3 1 M5 3 148 893 SHEET 2 BF 4 INVENTOR Mafthew L. Spillane ATTORNEY PATENIED FIG. 3

SOURCE v Bfiw gginz INVENTOR Matthew L. Spillane ATTORNEY PAIENTEB JUL31 I973 SHEEI 0F 4 INVENTOR Matthew L. Spillane BY ATTORNEY METHOD ANDAPPARATUSFORDETECTING DEFECTIVE SHELLS Shells used for making blastingcaps must be free of defects such as holes, cracks, or deformities(e.g., outof-roundness) which would allow moisture to enterdesensitizing them. The defects can also let explosive material spillout of the cap during assembly, leaving the cap less powerful andcausing a dangerous situation on the assembly line. Until now, shellswere not systematically tested for defects as no fast, inexpensivemethod of accurately testing large numbers of shells was available.Rather, a sampling of finished caps was placed in water at 150/ lbs/sq.in. and then shot. If too many failed, the entire lot had to bediscarded. That method was, of course, wasteful of good caps as well asthe materials that were used to fill the defective shells.

I have invented an apparatus and method for detecting defects in shellsbefore they are filled. My method and apparatus can rapidly, accurately,inexpensively, and simultaneously test large numbers of shells. Holes sosmall that they cannot be seen with the naked eye are readily detectablewith this invention. Also, a hole in a shell usually produces a whistleas the shell is being tested which immediately attracts the operatorsattention to the defective shell.

Each shell is provided with a friction seal in its open end. The shellis held on the friction seal while a limited quantity of gas is admittedinto the inside of the shell at a pressure sufficient to force the shellofi the seal were it not being held on the seal. After a short interval,the gas pressure is allowed to push the shell off the seal. If the shellis not defective, it will be pushed off; but, if it has a hole or crackin it, the gas will have escaped through the hole or crack and the shellwill remain stuck to the friction seal where it can be removed anddiscarded by hand or by a machine. The shell will also remain stuck tothe friction seal if it is deformed at the mouth so that there is a verytight fit between the shell and the friction seal.

The accompanying drawings illustrate certain presently preferredembodiments of this invention.

FIG. 1 is a front view partially in section of the apparatus of thisinvention.

FIG. 2 is a front view partially in section of the nipple and partssurrounding it as shown in FIG. 1.

FIG. 3 is a schematic drawing of the pneumatic system for the apparatusof FIG. 1.

FIG. 4 is an electrical diagram for the apparatus of FIGS. 1 and 2.

In FIG. 1, a main support 1 made up of many structural members, supportsan air cylinder 2 which can be activated to raise or lower bed 3. To bed3 are fixed arms 4 which ride against tracks 5. Bed 3 holds a tray 6 inwhich may be placed shells such as shell 7 arranged in a pattern of 7rows of 14 shells alternating with 8 rows of 13 shells or other suitablepattern. Stops 8 and 9 are also fixed to bed 3, stop 8 being directlybelow limit switch 10. Upper support 11 is attached to main support 1.The upper support holds an air chamber (shown in FIG. 2) which suppliesair to nipples such as nipple 12 arranged in a pattern of 7 rows of 14nipples alternating with 8 rows of 13 nipples corresponding to thepositions of the shells. Also shown in FIG. 1 are the positions of theemergency reverse button 13, the air pressure gauge 14 which shows thepressure in the air chamber, the control box 15, and a start switch l6.

In FIG. 2, walls 17 and 18 form an air chamber 19. Nipple 12 is mountedon wall 18. A check valve 20 which permits air to flow only in adownward direction is mounted on chamber wall 18 above the nipple andair passage 21 leads from air chamber 19 through check valve 20, chamberwall 18, and nipple l2. Nipple 12 is provided with a four-lobed ringseal 22 held in recess 23. A side air passage 24 leads from air passage21 to the inside rim of four-lobed ring seal 22. Air prssure against theinside rim of seal 22 causes it to expand outwardly, giving an excellentsealing effect in spite of small variations in the diameter of shell 7.

In FIG. 3, a source of air pressure at about lbs/sq. in. is supplied toon-off valve 25 which is connected to check valve 26 and air cleaner 27by lines 78. Air cleaner 27 is connected to a dryer 28 which, in turn,is connected to spring-biased solenoid valve 29 which is controlled bysolenoid 30. Air from this valve goes to chamber 19 (FIG. 2). Checkvalve 26 is connected to a second air cleaner 31, then to an on-offvalve 32 and, by way of lines 33, to solenoid valves 34 and 35; solenoidvalve 34 is controlled'by solenoids 36 and 37. Air from solenoid valve34 goes to solenoid valves 35 and 38 by way of lines 39 and 40 andcontrols these valves as will hereinafter be explained. Air from valve35 goes to cylinder 47 and air from valve 38 goes to cylinder 42. Thesecylinders contain oil 43 which can flow through speed control valves 44and 45 into cylinder 2. This cylinder contains a piston 46 which isconnected by shaft 47 to bed 3 (FIG. 1). Oil is used because it gives asmoother movement than air.

The operation of the apparatus of FIGS. 1, 2, and 3 will now bedescribed in conjunction with the description of FIG. 4.

A tray of shells to be tested is placed as shown in FIG.. 1. In FIG. 3,valves 25 and 32 are turned to the ON position as shown. In FIG. 4, asource of electricity is provided to hot line A and 2-pole switch 48 isturned to the ON POSITION. Using an electrical convention, the contactsmove up or down according to the position of the asterisk on the sameside of the switch as the position to which the switch is turned. Acurrent flows through line 49 operating dryer 28.

The operator then selects the mode of operation. There are three modesthe manual mode, the dwell up mode, and the automatic mode.

In the manual mode the operator can only raise and lower the bed; thismode will be described first. Twopole mode switch 50 is set to MAN," thecontacts moving to the upper position. Current now flows through lines51 and 52 to start switch 16, and through line 53 to a second startswitch 54 (Two start switches are used so that the operator must keepboth hands away from the moving portions of the apparatus). The currentcontinues through line 55 through mode switch 50, through lines 56 and57 to solenoid 36. This solenoid causes solenoid valve 34 (FIG. 3) toremain as shown which lets air flow from lines 39 to valves 38 and 35.Valve 38 permits air in the top of cylinder 43 to be exhausted and valve35 lets air flow from line 33 into the top of cylinder 41 which keepspiston 46 as shown holding bed 3 in the position shown in FIG. 1. Thecircuit to solenoid 36 is completed to ground by way of lines 58 and 59.

The operator then presses switch 16 with one hand and switch 54 with theother hand. These switches are spring-biased to the position shown inFIG. 4.

Current now flows from line 52 through switch 16, line 60, switch 54,and line 61 to solenoid 37 to lines 62 and 59. Solenoid 37 in FIG. 3moves valve 34 so that air flows through lines 40 moving valves 35 and38 so that air in cylinder 41 exhausts through valve 35 and air in line33, by way of valve 38, forces oil into the bottom of cylinder 3 causingbed 3 (FIG. 1) to move so that the tray and shells will be in theposition shown in FIG. 2, ready for testing. Releasing switches 16 and54 returns bed 3 to the position of FIG. 1.

In the Dwell Up mode, the contacts of mode switch 50 remain as shown.When the operator presses switches 16 and 54, bed 3 will rise as before,but releasing switches 16, 54, or both will not cause the bed to lowersince mode switch 50 is open. The Manual and Dwell Up modes are usedprimarily for servicing the machine.

In the Automatic mode, the contacts in mode switch 50 move to the lowerposition. When the operator closes switches 16 and 54, bed 3 rises asbefore. When the bed reaches its uppermost position so that the nippleshave entered the shells and testing may proceed, stop 8 (FIG. 1) closeslimit switch 9 (FIGS. 1 and 3). Current then flows through line 51, modeswitch 50, line 63, limit switch 9, and line 64 to normally-closedswitch 65 to solenoid 30 to line 59. Solenoid 30 is immediatelyactivated and lets air flow through valve 29 from dryer 28 (FIG. 3) toair chamber 19 (FIG. 2) and, by way of air passages 21, all of theshells.

When limit switch 9 was closed, current also flowed from line 64 totimers 66 and 67 to lines 68 and 69, respectively, to line 59. Timer 66opens switch 65 after the pressure in the line from dryer 28 and thepressure in the non-defective shells have had enough time to equalize(about 2 seconds). When switch 65 is opened, valve 29 returns to theposition shown in FIG. 3 which exhausts air chamber 19. The pressure inthe nondefective shells remains high due to check valves 20 but the airin defective shells quickly leaks out the holes and cracks and thepressure in these shells drops to atmospheric pressure. After asufficient amount of time has passed to permit leakage through thedefective shells (about 4 seconds), timer 67 closes switch 70 permittingcurrent to flow to solenoid 36 which lowers bed 3. Air pressure in thenon-defective shells forces the shells off seal 22 (FIG. 2) and theyremain in the tray as it is lowered. Friction between the defectiveshells and seal 22 holds the defective shells on seal 22 as the tray islowered. These shells are then pulled OE and discarded.

Closing emergency reverse switch 13 permits current to flow throughlines 71, 72, and 57 to solenoid 36 which lowers bed 3 in the event ofan emergency.

It should be noted that it is also within the scope of this invention tolower the nipples instead of raising the tray.

I claim:

1. An apparatus for detecting a hole in a shell sealed at one end andopen at the other comprising:

1. sealing means for sealing the open end of said shell by projectinginto said open end of said shell to form a friction engagement therewithand the frictional force being sufficient to support the weight of saidshell, said sealing means having a gas passage therethrough;

2. means for temporarily holding said shell and said sealing means insealed relationship; and

3. a source of gas to said gas passage, said source being of a limitedquantity, the pressure of said gas being great enough to overcome saidfriction and force a shell without a hole therethrough off said sealingmeans.

2. An apparatus according to claim 1 wherein said gas pressure is airpressure.

3. An apparatus according to claim 1 wherein a oneway valve permits gasto move through said gas passage only in the direction of said shell.

4. An apparatus according to claim 1 wherein said gas is supplied tosaid shell through a nipple and said means for temporarily holding saidshell and said sealing means in sealed relationship is an air cylinderwhich moves said shell relative to said nipple until said nipple hasentered said shell.

5. An apparatus according to claim 4 wherein said sealing means is afour-lobed ring seal in a recess in said nipple.

6. An apparatus according to claim 5 wherein a side passage communicatesfrom said gas passage to the inner side of said four-lobed ring seal.

7. An apparatus for detecting holes in shells comprismg:

a. a tray for holding said shells in a vertical position;

b. nipples, each having a gas passage therethrough and each beingpositioned directly above a shell;

c. means for moving said tray relative to said nipples;

d. sealing means for friction sealing each nipple to the shell itprojects into and the frictional force being sufficient to support theweight of said shell; and

e. means for supplying a limited quantity of gas to each gas passage ata pressure sufficient to overcome said friction and force a shellwithout a hole therethrough off said sealing means.

8. An apparatus according to claim 7 wherein a check valve is providedin each gas passage.

9. An apparatus according to claim 7 wherein said sealing means is afour-lobed ring seal in a recess in said nipple and a side passagecommunicates from said gas passage to the inner side of said four-lobedring seal.

10. A method of detecting a hole in a shell sealed at one end and openat the other comprising:

a. inserting a friction seal having a gas passage therethrough into theopen end of said shell;

b. holding said shell on said friction seal;

c. supplying a limited quantity of gas through said gas passage to theinside of said shell at a pressure greater than the pressure needed toforce said shell off said friction seal;

d. waiting a sufficient amount to permit enough of said gas to passthrough said hole to reduce the pressure of said gas below the pressureneeded to force said shell off said friction seal; and

e. ceasing holding said shell on said friction seal.

it 1 i i

1. An apparatus for detecting a hole in a shell sealed at one end andopen at the other comprising:
 1. sealing means for sealing the open endof said shell by projecting into said open end of said shell to form afriction engagement therewith and the frictional force being sufficientto support the weight of said shell, said sealing means having a gaspassage therethrough;
 2. means for temporarily holding said shell andsaid sealing means in sealed relationship; and
 3. a source of gas tosaid gas passage, said source being of a limited quantity, the pressureof said gas being great enough to overcome said friction and force ashell without a hole therethrough off said sealing means.
 2. means fortemporarily holding said shell and said sealing means in sealedrelationship; and
 2. An apparatus according to claim 1 wherein said gaspressure is air pressure.
 3. An apparatus according to claim 1 wherein aone-way valve permits gas to move through said gas passage only in thedirection of said shell.
 3. a source of gas to said gas passage, saidsource being of a limited quantity, the pressure of said gas being greatenough to overcome said friction and force a shell without a holetherethrough off said sealing means.
 4. An apparatus according to claim1 wherein said gas is supplied to said sheLl through a nipple and saidmeans for temporarily holding said shell and said sealing means insealed relationship is an air cylinder which moves said shell relativeto said nipple until said nipple has entered said shell.
 5. An apparatusaccording to claim 4 wherein said sealing means is a four-lobed ringseal in a recess in said nipple.
 6. An apparatus according to claim 5wherein a side passage communicates from said gas passage to the innerside of said four-lobed ring seal.
 7. An apparatus for detecting holesin shells comprising: a. a tray for holding said shells in a verticalposition; b. nipples, each having a gas passage therethrough and eachbeing positioned directly above a shell; c. means for moving said trayrelative to said nipples; d. sealing means for friction sealing eachnipple to the shell it projects into and the frictional force beingsufficient to support the weight of said shell; and e. means forsupplying a limited quantity of gas to each gas passage at a pressuresufficient to overcome said friction and force a shell without a holetherethrough off said sealing means.
 8. An apparatus according to claim7 wherein a check valve is provided in each gas passage.
 9. An apparatusaccording to claim 7 wherein said sealing means is a four-lobed ringseal in a recess in said nipple and a side passage communicates fromsaid gas passage to the inner side of said four-lobed ring seal.
 10. Amethod of detecting a hole in a shell sealed at one end and open at theother comprising: a. inserting a friction seal having a gas passagetherethrough into the open end of said shell; b. holding said shell onsaid friction seal; c. supplying a limited quantity of gas through saidgas passage to the inside of said shell at a pressure greater than thepressure needed to force said shell off said friction seal; d. waiting asufficient amount to permit enough of said gas to pass through said holeto reduce the pressure of said gas below the pressure needed to forcesaid shell off said friction seal; and e. ceasing holding said shell onsaid friction seal.